For most of the competitors yesterday, the Mobil 1 Invitational was the completion of a long weekend in which they left much of their energy at Friday's Millrose Games in New York.

Two runners, Paul Ereng and Michael Johnson, bypassed the prestigious Millrose meet and focused on races here. In each case, the result was a meet record, Ereng clocking 1 minute 48.06 seconds in the 800 meters and Johnson 46.23 in the 400 meters.

"There were only two athletes I wanted that I didn't get, Ereng and Johnson," said Howard Schmertz, the Millrose Games director who watched the Mobil 1 from the infield of the George Mason University Recreation Sports Complex.

Schmertz was not happy with the claim by Ereng, the Olympic 800-meter champion, that he had not been invited to the Millrose meet. Schmertz said he had made a monetary offer, which was rejected. But Ereng's defection apparently was more concerned with his historic inability to handle a banked board track. The Mobil 1 meet is held on an unbanked synthetic surface and Ereng had no trouble beating a good field that included the Millrose winner and former Mobil 1 record holder, Ray Brown.

"I said I would go for a fast time and that was the fastest time of the year, so I am happy with it," said Ereng, although he did not approach the world indoor record of 1:44.84 he set in Budapest in 1989.

That came in the World Indoor Championships and Ereng thinks he can beat it, possibly in this year's edition at Seville, Spain. There is a complication, however. Ereng's midterm examinations at the University of Virginia, where he is a junior, will end March 8, the same day the World Indoors begin.

He no longer competes for Virginia, because collegians can't take money to run and he earns lots of it. For example, he is unsure whether he will run in the Vitalis/Meadowlands Invitational Feb. 8 because he is also being wooed by a meet in Germany.

Eventually, he wants to attend law school and become a politician in his native Kenya. He displayed his qualifications yesterday when confronted with his remarks that implied he had skipped the Millrose meet because it is a declining event.

"The Millrose has always been the big indoor meet, overshadowing the others. Now the Mobil meet is gaining in prestige. That was all I meant," he said, passing the test.

He holds what Johnson wants, an Olympic gold medal. As the first man ever ranked No. 1 in both the 200 and 400 meters, Johnson's major problem would appear to be deciding which event to choose, because the schedule at Barcelona precludes an Olympic double in 1992.

After he fought off world indoor record holder Thomas Schoenlebe of Germany to win the 400 yesterday, Johnson was leaning more toward the 200, the event in which he set a U.S. indoor record of 20.55 last week at Lievin, France.

"I ran a poor race in France and I was shocked at the time," Johnson said. "I hadn't worked on speed, but I have good natural speed. I didn't know it would carry me that far."

He tired yesterday near the finish line of the 400. Later, he became dizzy during a media interview and sought treatment from a trainer. Afterward, he answered more questions.

"I hadn't run an indoor 400 since February of last year," he said. "It wasn't easy. I had to take a chance going out like I did. What makes it hard for a 200 runner going up to 400 is that you have to pace yourself the first 200. The other guys are used to it."

A Baylor graduate, he stayed away from the Millrose meet because he set up a low-key schedule of just three indoor races. He is determined not to be caught up in the pack that will take money to run anywhere, anytime.

"I don't want to be known as somebody who came in, smashed everybody one year and was never heard from again," he said. "It's not hard to pass up some things when you're looking long term. I think there are good things to come, if I pace myself."